With the proceeding of modern manufacturing technologies, the liquid crystal display (LCD) has been in widespread use. The working principles of the LCD are using an electric field to control the arrangement of liquid crystal molecules and displaying brilliant or dark images by the beams of the backlight which have passed the liquid crystal molecules or not. The performance of a liquid crystal display extremely depends on the properties of the optical components implemented therein, especially the quality of the color filter (CF) configured therein.
Please refer to FIG. 1, which shows a fabrication process for a color filter according to the prior art. As shown in FIG. 1, a transparent and polished oxidated layer 102 is formed on a silicon substrate 101. Then the oxidated layer 102 is covered with a blue photoresist. After a lithography process is provided, the blue pixels 1031 are formed. Next, the green pixels 1032 are formed by covering a green photoresist on the oxidated layer 102 and proceeding two lithography processes with a 25% pattern proportion. After covering a red photoresist on them and proceeding a lithography process, the red pixels 1033 are formed. Finally, another transparent and polished oxidated layer 104 is formed to cover the pixels and the silicon substrate 101, so that a whole color filter 100 is fabricated.
However, such a process has two disadvantages as follows:
First, during the manufacturing process of the pixels, the pixels of different colors would easily overlap or cover with each other because of the misalignment. The gaps between different pixels lead to the interference of light. To prevent this defect, the process of the green pixels 1032 must have two lithography processes, which increases the cost substantially.
Second, the different coating thickness of the blue photoresist, green photoresist and red photoresist result in a surface with a high roughness. The roughness cause the pixels of different colors to have different photo-transmission rates, which may influence the performance of the color filter 100.
To solve the problems, a method for fabricating a color filter is disclosed in the Taiwan Patent No. 00533589. The method includes steps of proceeding two lithography processes to respectively form the blue pixels 1031 and the red pixels 1033, and proceeding an etch-back process thereon to reveal the surfaces of the blue pixels 1031 and the red pixels 1033 covered by a green photoresist. Through this method, the accomplished blue pixels, red pixels 1033 and green pixels 1032 may have an identical thickness.
However, this improved method still fails to control the thickness of different pixels well. Moreover, although one lithography process of the green pixels 1032 manufacturing process is omitted, the cost down is still limited since an additional etching process is needed.
It is therefore attempted by the applicant to deal with the above situation encountered in the prior art.